The present invention relates to a spraying head as defined in the preamble of claim 1 for humidifying intake air with an aqueous mist.
The exhaust gases of piston engines, in particular diesel engines, contain many kinds of noxious combustion products. At the high combustion temperatures, the combustion process in the cylinder of a piston engine produces nitrogen oxides (NOx), which are emitted together with the exhaust gases into the atmosphere. Because of the negative environmental effects of nitrogen oxide emissions, efforts are undertaken to minimize their production.
As is known, adding water to the combustion process reduces the generation of nitrogen oxides. This phenomenon is based on the cooling effect of water. In practice, the introduction of water into the combustion process in a piston engine is often implemented by injecting water into the intake air. These arrangements are advantageous in respect of the shaft efficiency of the engine. The maximum amount of water introduced into the combustion space of the engine may be that amount which will remain in gaseous form in the intake air pressure and temperature conditions.
It has been established that introducing water mist into the intake air is a very advantageous and effective method of reducing noxious emissions. The spraying heads disclosed by the invention are used especially in connection with the humidification of the intake air of engines. When the spraying head is mounted in its position of application in the air intake duct of the engine, e.g. in connection with a turbocharged diesel engine before and/or after the compressor of the turbocharger, before and/or after a possible intercooler, it is subjected to very demanding conditions. The intake air flow rate in the air intake duct is e.g. of the order of 80 m/s. The temperature may also be fairly high, e.g. above 100 degrees C. In addition, the nozzles used must not be an obstruction to the intake air flow when they are not in use. An additional impediment may be the clogging of the nozzles especially when the nozzle head is not in use.
The object of the invention is to achieve a completely new type of spraying head that allows the intake air to be humidified when necessary and that forms no impediment to the intake air flow when not in use.
The spraying head of the invention is characterized in that the spraying head 1 is movable between at least two positions, a first position, in which first position the spraying head is retracted, and a second position, in which second position the spraying head is protruding.
The spraying head of the invention is additionally characterized by what is stated in claims 2–11.
The solution of the invention has numerous significant advantages. By implementing the spraying head so that it pops up when activated and is retracted when in non-active state, a spraying head solution is achieved that forms no obstruction to intake air flow when not in use. In addition, the solution disclosed allows the nozzles to remain clean. Providing the spraying head holder with a guide element and the spraying head, preferably its shank, with a mating element for the guide surface makes it possible to maintain a desired directional orientation of the nozzles. By providing the nozzle head with several nozzles, very effective humidification of intake air is achieved. By using the liquid to be sprayed as a pressure medium, a very advantageous and efficient solution is achieved. By providing a spring element for returning the spraying head into the retracted position, a faster and more effective transition to the retracted position is achieved.